8.25 swap for a 9.25 rear end assistance needed

[71GTX440]

I currently have a 1971 8.25 rear diff under my ride, looking at swapping for a newer dodge 9.25 rear end with disc brakes and 3.92 gears. What all will be needed for this to happen? Any help would be greatly appreciated!

 

[dasol7172]

How close is the 9.25 in width to a B body rear? Otherwise I think it would be a matter of cutting and re-welding the perches to the same B body position and some new U bolts. Not sure about pinion angle and all that though. Or driveshaft.

 

[71GTX440]

I honestly cannot find any good reference material online. I found a ton of info for Mopar rear ends from the 1970's, but nothing showing similar for more modern rear ends.

 

[Cranky]

I honestly cannot find any good reference material online. I found a ton of info for Mopar rear ends from the 1970's, but nothing showing similar for more modern rear ends.

Yeah, it's hard to find material on line because it's not a very popular swap. You might have to get on a couple or more sites to try and find others who have done it. Any reason why you don't want to do an 8 3/4 instead?

 

[HEMI-ITIS]

I never measured but I thing the d60 in my heap came outta an "E"body.

 

[nstyle73]

Well, one issue will be your donor rear. Depending on the source, the width might not be correct, and if its a newer truck rear end, the pumpkin may not be centered which is a no-go. Secondly, depending on how new it is and if it is a truck rear, the bolt pattern is 5x5.5 instead of 5x4.5. I explored this option for about the 3 minutes it took to crawl under a 2003 Ram. However, I am not completely convinced that with some ingenuity, the 14" rotors and calipers won't work. The tube flanges appear to be the same but I have not pulled everything off to check the caliper mounts etc. The bolt pattern could be overcome in my case as I am 2" narrower than I need so I can run 1" wheel adapters.

 

[nstyle73]

Well, one issue will be your donor rear. Depending on the source, the width might not be correct, and if its a newer truck rear end, the pumpkin may not be centered which is a no-go. Secondly, depending on how new it is and if it is a truck rear, the bolt pattern is 5x5.5 instead of 5x4.5. I explored this option for about the 3 minutes it took to crawl under a 2003 Ram. The rear is a 4.56 with a Detroit locker and has lived behind a 580hp 6.1 based 426. They are "weak" but maybe this one lived because of the lack of traction. However, I am not completely convinced that with some ingenuity, the 14" rotors and calipers won't work. The tube flanges appear to be the same but I have not pulled everything off to check the caliper mounts etc. The bolt pattern in the rotors could be overcome in my case as I am 2" narrower than I need so I can run 1" wheel adapters.

 

[bm02tj]

I swapped a 9 1/4 for a 8 1/4 and needed a new drive shaft
or have yours shortened and larger yoke installed
again check width and bolt pattern

 

[Ryan.C]

A few questions regarding your swap.

What car did you do this swap on?
What car did the 9 1/4 come from?
Was the 9 1/4 the same width drum to drum?

Thanks much!

 

[bm02tj]

73 SSB and it came from a 76 cop car fullsize
and yes width wise it was same if I remember right
I did this 35 years ago
and I still have car that I hope to fix damage from my youngest daughter from about 20 years ago
has been parked in dry storage so next year

 

[Daves69]

I'm thinking my '05 Ram is around 62" flange to flange. A "D" body truck I think is closer to a "B" body.
Some info here.............
https://www.hemmings.com/magazine/mus/2005/12/Chrysler-9-1-4-inch-differentials/1281744.html